/*
 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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/*
 * (C) Copyright Taligent, Inc. 1996 - All Rights Reserved
 * (C) Copyright IBM Corp. 1996 - All Rights Reserved
 *
 *   The original version of this source code and documentation is copyrighted
 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
 * materials are provided under terms of a License Agreement between Taligent
 * and Sun. This technology is protected by multiple US and International
 * patents. This notice and attribution to Taligent may not be removed.
 *   Taligent is a registered trademark of Taligent, Inc.
 *
 */

package java.text;

import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.lang.ref.SoftReference;
import java.text.spi.DateFormatSymbolsProvider;
import java.util.Arrays;
import java.util.Locale;
import java.util.Objects;
import java.util.ResourceBundle;
import java.util.TimeZone;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import sun.util.locale.provider.LocaleProviderAdapter;
import sun.util.locale.provider.LocaleServiceProviderPool;
import sun.util.locale.provider.ResourceBundleBasedAdapter;
import sun.util.locale.provider.TimeZoneNameUtility;

/**
 * <code>DateFormatSymbols</code> is a public class for encapsulating
 * localizable date-time formatting data, such as the names of the
 * months, the names of the days of the week, and the time zone data.
 * <code>SimpleDateFormat</code> uses
 * <code>DateFormatSymbols</code> to encapsulate this information.
 *
 * <p>
 * Typically you shouldn't use <code>DateFormatSymbols</code> directly.
 * Rather, you are encouraged to create a date-time formatter with the
 * <code>DateFormat</code> class's factory methods: <code>getTimeInstance</code>,
 * <code>getDateInstance</code>, or <code>getDateTimeInstance</code>.
 * These methods automatically create a <code>DateFormatSymbols</code> for
 * the formatter so that you don't have to. After the
 * formatter is created, you may modify its format pattern using the
 * <code>setPattern</code> method. For more information about
 * creating formatters using <code>DateFormat</code>'s factory methods,
 * see {@link DateFormat}.
 *
 * <p>
 * If you decide to create a date-time formatter with a specific
 * format pattern for a specific locale, you can do so with:
 * <blockquote>
 * <pre>
 * new SimpleDateFormat(aPattern, DateFormatSymbols.getInstance(aLocale)).
 * </pre>
 * </blockquote>
 *
 * <p>
 * <code>DateFormatSymbols</code> objects are cloneable. When you obtain
 * a <code>DateFormatSymbols</code> object, feel free to modify the
 * date-time formatting data. For instance, you can replace the localized
 * date-time format pattern characters with the ones that you feel easy
 * to remember. Or you can change the representative cities
 * to your favorite ones.
 *
 * <p>
 * New <code>DateFormatSymbols</code> subclasses may be added to support
 * <code>SimpleDateFormat</code> for date-time formatting for additional locales.
 *
 * @author Chen-Lieh Huang
 * @see DateFormat
 * @see SimpleDateFormat
 * @see java.util.SimpleTimeZone
 */
public class DateFormatSymbols implements Serializable, Cloneable {

  /**
   * Construct a DateFormatSymbols object by loading format data from
   * resources for the default {@link java.util.Locale.Category#FORMAT FORMAT}
   * locale. This constructor can only
   * construct instances for the locales supported by the Java
   * runtime environment, not for those supported by installed
   * {@link java.text.spi.DateFormatSymbolsProvider DateFormatSymbolsProvider}
   * implementations. For full locale coverage, use the
   * {@link #getInstance(Locale) getInstance} method.
   * <p>This is equivalent to calling
   * {@link #DateFormatSymbols(Locale)
   * DateFormatSymbols(Locale.getDefault(Locale.Category.FORMAT))}.
   *
   * @throws java.util.MissingResourceException if the resources for the default locale cannot be
   * found or cannot be loaded.
   * @see #getInstance()
   * @see java.util.Locale#getDefault(java.util.Locale.Category)
   * @see java.util.Locale.Category#FORMAT
   */
  public DateFormatSymbols() {
    initializeData(Locale.getDefault(Locale.Category.FORMAT));
  }

  /**
   * Construct a DateFormatSymbols object by loading format data from
   * resources for the given locale. This constructor can only
   * construct instances for the locales supported by the Java
   * runtime environment, not for those supported by installed
   * {@link java.text.spi.DateFormatSymbolsProvider DateFormatSymbolsProvider}
   * implementations. For full locale coverage, use the
   * {@link #getInstance(Locale) getInstance} method.
   *
   * @param locale the desired locale
   * @throws java.util.MissingResourceException if the resources for the specified locale cannot be
   * found or cannot be loaded.
   * @see #getInstance(Locale)
   */
  public DateFormatSymbols(Locale locale) {
    initializeData(locale);
  }

  /**
   * Era strings. For example: "AD" and "BC".  An array of 2 strings,
   * indexed by <code>Calendar.BC</code> and <code>Calendar.AD</code>.
   *
   * @serial
   */
  String eras[] = null;

  /**
   * Month strings. For example: "January", "February", etc.  An array
   * of 13 strings (some calendars have 13 months), indexed by
   * <code>Calendar.JANUARY</code>, <code>Calendar.FEBRUARY</code>, etc.
   *
   * @serial
   */
  String months[] = null;

  /**
   * Short month strings. For example: "Jan", "Feb", etc.  An array of
   * 13 strings (some calendars have 13 months), indexed by
   * <code>Calendar.JANUARY</code>, <code>Calendar.FEBRUARY</code>, etc.
   *
   * @serial
   */
  String shortMonths[] = null;

  /**
   * Weekday strings. For example: "Sunday", "Monday", etc.  An array
   * of 8 strings, indexed by <code>Calendar.SUNDAY</code>,
   * <code>Calendar.MONDAY</code>, etc.
   * The element <code>weekdays[0]</code> is ignored.
   *
   * @serial
   */
  String weekdays[] = null;

  /**
   * Short weekday strings. For example: "Sun", "Mon", etc.  An array
   * of 8 strings, indexed by <code>Calendar.SUNDAY</code>,
   * <code>Calendar.MONDAY</code>, etc.
   * The element <code>shortWeekdays[0]</code> is ignored.
   *
   * @serial
   */
  String shortWeekdays[] = null;

  /**
   * AM and PM strings. For example: "AM" and "PM".  An array of
   * 2 strings, indexed by <code>Calendar.AM</code> and
   * <code>Calendar.PM</code>.
   *
   * @serial
   */
  String ampms[] = null;

  /**
   * Localized names of time zones in this locale.  This is a
   * two-dimensional array of strings of size <em>n</em> by <em>m</em>,
   * where <em>m</em> is at least 5.  Each of the <em>n</em> rows is an
   * entry containing the localized names for a single <code>TimeZone</code>.
   * Each such row contains (with <code>i</code> ranging from
   * 0..<em>n</em>-1):
   * <ul>
   * <li><code>zoneStrings[i][0]</code> - time zone ID</li>
   * <li><code>zoneStrings[i][1]</code> - long name of zone in standard
   * time</li>
   * <li><code>zoneStrings[i][2]</code> - short name of zone in
   * standard time</li>
   * <li><code>zoneStrings[i][3]</code> - long name of zone in daylight
   * saving time</li>
   * <li><code>zoneStrings[i][4]</code> - short name of zone in daylight
   * saving time</li>
   * </ul>
   * The zone ID is <em>not</em> localized; it's one of the valid IDs of
   * the {@link java.util.TimeZone TimeZone} class that are not
   * <a href="../java/util/TimeZone.html#CustomID">custom IDs</a>.
   * All other entries are localized names.
   *
   * @serial
   * @see java.util.TimeZone
   */
  String zoneStrings[][] = null;

  /**
   * Indicates that zoneStrings is set externally with setZoneStrings() method.
   */
  transient boolean isZoneStringsSet = false;

  /**
   * Unlocalized date-time pattern characters. For example: 'y', 'd', etc.
   * All locales use the same these unlocalized pattern characters.
   */
  static final String patternChars = "GyMdkHmsSEDFwWahKzZYuXL";

  static final int PATTERN_ERA = 0; // G
  static final int PATTERN_YEAR = 1; // y
  static final int PATTERN_MONTH = 2; // M
  static final int PATTERN_DAY_OF_MONTH = 3; // d
  static final int PATTERN_HOUR_OF_DAY1 = 4; // k
  static final int PATTERN_HOUR_OF_DAY0 = 5; // H
  static final int PATTERN_MINUTE = 6; // m
  static final int PATTERN_SECOND = 7; // s
  static final int PATTERN_MILLISECOND = 8; // S
  static final int PATTERN_DAY_OF_WEEK = 9; // E
  static final int PATTERN_DAY_OF_YEAR = 10; // D
  static final int PATTERN_DAY_OF_WEEK_IN_MONTH = 11; // F
  static final int PATTERN_WEEK_OF_YEAR = 12; // w
  static final int PATTERN_WEEK_OF_MONTH = 13; // W
  static final int PATTERN_AM_PM = 14; // a
  static final int PATTERN_HOUR1 = 15; // h
  static final int PATTERN_HOUR0 = 16; // K
  static final int PATTERN_ZONE_NAME = 17; // z
  static final int PATTERN_ZONE_VALUE = 18; // Z
  static final int PATTERN_WEEK_YEAR = 19; // Y
  static final int PATTERN_ISO_DAY_OF_WEEK = 20; // u
  static final int PATTERN_ISO_ZONE = 21; // X
  static final int PATTERN_MONTH_STANDALONE = 22; // L

  /**
   * Localized date-time pattern characters. For example, a locale may
   * wish to use 'u' rather than 'y' to represent years in its date format
   * pattern strings.
   * This string must be exactly 18 characters long, with the index of
   * the characters described by <code>DateFormat.ERA_FIELD</code>,
   * <code>DateFormat.YEAR_FIELD</code>, etc.  Thus, if the string were
   * "Xz...", then localized patterns would use 'X' for era and 'z' for year.
   *
   * @serial
   */
  String localPatternChars = null;

  /**
   * The locale which is used for initializing this DateFormatSymbols object.
   *
   * @serial
   * @since 1.6
   */
  Locale locale = null;

  /* use serialVersionUID from JDK 1.1.4 for interoperability */
  static final long serialVersionUID = -5987973545549424702L;

  /**
   * Returns an array of all locales for which the
   * <code>getInstance</code> methods of this class can return
   * localized instances.
   * The returned array represents the union of locales supported by the
   * Java runtime and by installed
   * {@link java.text.spi.DateFormatSymbolsProvider DateFormatSymbolsProvider}
   * implementations.  It must contain at least a <code>Locale</code>
   * instance equal to {@link java.util.Locale#US Locale.US}.
   *
   * @return An array of locales for which localized <code>DateFormatSymbols</code> instances are
   * available.
   * @since 1.6
   */
  public static Locale[] getAvailableLocales() {
    LocaleServiceProviderPool pool =
        LocaleServiceProviderPool.getPool(DateFormatSymbolsProvider.class);
    return pool.getAvailableLocales();
  }

  /**
   * Gets the <code>DateFormatSymbols</code> instance for the default
   * locale.  This method provides access to <code>DateFormatSymbols</code>
   * instances for locales supported by the Java runtime itself as well
   * as for those supported by installed
   * {@link java.text.spi.DateFormatSymbolsProvider DateFormatSymbolsProvider}
   * implementations.
   * <p>This is equivalent to calling {@link #getInstance(Locale)
   * getInstance(Locale.getDefault(Locale.Category.FORMAT))}.
   *
   * @return a <code>DateFormatSymbols</code> instance.
   * @see java.util.Locale#getDefault(java.util.Locale.Category)
   * @see java.util.Locale.Category#FORMAT
   * @since 1.6
   */
  public static final DateFormatSymbols getInstance() {
    return getInstance(Locale.getDefault(Locale.Category.FORMAT));
  }

  /**
   * Gets the <code>DateFormatSymbols</code> instance for the specified
   * locale.  This method provides access to <code>DateFormatSymbols</code>
   * instances for locales supported by the Java runtime itself as well
   * as for those supported by installed
   * {@link java.text.spi.DateFormatSymbolsProvider DateFormatSymbolsProvider}
   * implementations.
   *
   * @param locale the given locale.
   * @return a <code>DateFormatSymbols</code> instance.
   * @throws NullPointerException if <code>locale</code> is null
   * @since 1.6
   */
  public static final DateFormatSymbols getInstance(Locale locale) {
    DateFormatSymbols dfs = getProviderInstance(locale);
    if (dfs != null) {
      return dfs;
    }
    throw new RuntimeException("DateFormatSymbols instance creation failed.");
  }

  /**
   * Returns a DateFormatSymbols provided by a provider or found in
   * the cache. Note that this method returns a cached instance,
   * not its clone. Therefore, the instance should never be given to
   * an application.
   */
  static final DateFormatSymbols getInstanceRef(Locale locale) {
    DateFormatSymbols dfs = getProviderInstance(locale);
    if (dfs != null) {
      return dfs;
    }
    throw new RuntimeException("DateFormatSymbols instance creation failed.");
  }

  private static DateFormatSymbols getProviderInstance(Locale locale) {
    LocaleProviderAdapter adapter = LocaleProviderAdapter
        .getAdapter(DateFormatSymbolsProvider.class, locale);
    DateFormatSymbolsProvider provider = adapter.getDateFormatSymbolsProvider();
    DateFormatSymbols dfsyms = provider.getInstance(locale);
    if (dfsyms == null) {
      provider = LocaleProviderAdapter.forJRE().getDateFormatSymbolsProvider();
      dfsyms = provider.getInstance(locale);
    }
    return dfsyms;
  }

  /**
   * Gets era strings. For example: "AD" and "BC".
   *
   * @return the era strings.
   */
  public String[] getEras() {
    return Arrays.copyOf(eras, eras.length);
  }

  /**
   * Sets era strings. For example: "AD" and "BC".
   *
   * @param newEras the new era strings.
   */
  public void setEras(String[] newEras) {
    eras = Arrays.copyOf(newEras, newEras.length);
    cachedHashCode = 0;
  }

  /**
   * Gets month strings. For example: "January", "February", etc.
   *
   * <p>If the language requires different forms for formatting and
   * stand-alone usages, this method returns month names in the
   * formatting form. For example, the preferred month name for
   * January in the Czech language is <em>ledna</em> in the
   * formatting form, while it is <em>leden</em> in the stand-alone
   * form. This method returns {@code "ledna"} in this case. Refer
   * to the <a href="http://unicode.org/reports/tr35/#Calendar_Elements">
   * Calendar Elements in the Unicode Locale Data Markup Language
   * (LDML) specification</a> for more details.
   *
   * @return the month strings.
   */
  public String[] getMonths() {
    return Arrays.copyOf(months, months.length);
  }

  /**
   * Sets month strings. For example: "January", "February", etc.
   *
   * @param newMonths the new month strings.
   */
  public void setMonths(String[] newMonths) {
    months = Arrays.copyOf(newMonths, newMonths.length);
    cachedHashCode = 0;
  }

  /**
   * Gets short month strings. For example: "Jan", "Feb", etc.
   *
   * <p>If the language requires different forms for formatting and
   * stand-alone usages, This method returns short month names in
   * the formatting form. For example, the preferred abbreviation
   * for January in the Catalan language is <em>de gen.</em> in the
   * formatting form, while it is <em>gen.</em> in the stand-alone
   * form. This method returns {@code "de gen."} in this case. Refer
   * to the <a href="http://unicode.org/reports/tr35/#Calendar_Elements">
   * Calendar Elements in the Unicode Locale Data Markup Language
   * (LDML) specification</a> for more details.
   *
   * @return the short month strings.
   */
  public String[] getShortMonths() {
    return Arrays.copyOf(shortMonths, shortMonths.length);
  }

  /**
   * Sets short month strings. For example: "Jan", "Feb", etc.
   *
   * @param newShortMonths the new short month strings.
   */
  public void setShortMonths(String[] newShortMonths) {
    shortMonths = Arrays.copyOf(newShortMonths, newShortMonths.length);
    cachedHashCode = 0;
  }

  /**
   * Gets weekday strings. For example: "Sunday", "Monday", etc.
   *
   * @return the weekday strings. Use <code>Calendar.SUNDAY</code>, <code>Calendar.MONDAY</code>,
   * etc. to index the result array.
   */
  public String[] getWeekdays() {
    return Arrays.copyOf(weekdays, weekdays.length);
  }

  /**
   * Sets weekday strings. For example: "Sunday", "Monday", etc.
   *
   * @param newWeekdays the new weekday strings. The array should be indexed by
   * <code>Calendar.SUNDAY</code>, <code>Calendar.MONDAY</code>, etc.
   */
  public void setWeekdays(String[] newWeekdays) {
    weekdays = Arrays.copyOf(newWeekdays, newWeekdays.length);
    cachedHashCode = 0;
  }

  /**
   * Gets short weekday strings. For example: "Sun", "Mon", etc.
   *
   * @return the short weekday strings. Use <code>Calendar.SUNDAY</code>,
   * <code>Calendar.MONDAY</code>, etc. to index the result array.
   */
  public String[] getShortWeekdays() {
    return Arrays.copyOf(shortWeekdays, shortWeekdays.length);
  }

  /**
   * Sets short weekday strings. For example: "Sun", "Mon", etc.
   *
   * @param newShortWeekdays the new short weekday strings. The array should be indexed by
   * <code>Calendar.SUNDAY</code>, <code>Calendar.MONDAY</code>, etc.
   */
  public void setShortWeekdays(String[] newShortWeekdays) {
    shortWeekdays = Arrays.copyOf(newShortWeekdays, newShortWeekdays.length);
    cachedHashCode = 0;
  }

  /**
   * Gets ampm strings. For example: "AM" and "PM".
   *
   * @return the ampm strings.
   */
  public String[] getAmPmStrings() {
    return Arrays.copyOf(ampms, ampms.length);
  }

  /**
   * Sets ampm strings. For example: "AM" and "PM".
   *
   * @param newAmpms the new ampm strings.
   */
  public void setAmPmStrings(String[] newAmpms) {
    ampms = Arrays.copyOf(newAmpms, newAmpms.length);
    cachedHashCode = 0;
  }

  /**
   * Gets time zone strings.  Use of this method is discouraged; use
   * {@link java.util.TimeZone#getDisplayName() TimeZone.getDisplayName()}
   * instead.
   * <p>
   * The value returned is a
   * two-dimensional array of strings of size <em>n</em> by <em>m</em>,
   * where <em>m</em> is at least 5.  Each of the <em>n</em> rows is an
   * entry containing the localized names for a single <code>TimeZone</code>.
   * Each such row contains (with <code>i</code> ranging from
   * 0..<em>n</em>-1):
   * <ul>
   * <li><code>zoneStrings[i][0]</code> - time zone ID</li>
   * <li><code>zoneStrings[i][1]</code> - long name of zone in standard
   * time</li>
   * <li><code>zoneStrings[i][2]</code> - short name of zone in
   * standard time</li>
   * <li><code>zoneStrings[i][3]</code> - long name of zone in daylight
   * saving time</li>
   * <li><code>zoneStrings[i][4]</code> - short name of zone in daylight
   * saving time</li>
   * </ul>
   * The zone ID is <em>not</em> localized; it's one of the valid IDs of
   * the {@link java.util.TimeZone TimeZone} class that are not
   * <a href="../util/TimeZone.html#CustomID">custom IDs</a>.
   * All other entries are localized names.  If a zone does not implement
   * daylight saving time, the daylight saving time names should not be used.
   * <p>
   * If {@link #setZoneStrings(String[][]) setZoneStrings} has been called
   * on this <code>DateFormatSymbols</code> instance, then the strings
   * provided by that call are returned. Otherwise, the returned array
   * contains names provided by the Java runtime and by installed
   * {@link java.util.spi.TimeZoneNameProvider TimeZoneNameProvider}
   * implementations.
   *
   * @return the time zone strings.
   * @see #setZoneStrings(String[][])
   */
  public String[][] getZoneStrings() {
    return getZoneStringsImpl(true);
  }

  /**
   * Sets time zone strings.  The argument must be a
   * two-dimensional array of strings of size <em>n</em> by <em>m</em>,
   * where <em>m</em> is at least 5.  Each of the <em>n</em> rows is an
   * entry containing the localized names for a single <code>TimeZone</code>.
   * Each such row contains (with <code>i</code> ranging from
   * 0..<em>n</em>-1):
   * <ul>
   * <li><code>zoneStrings[i][0]</code> - time zone ID</li>
   * <li><code>zoneStrings[i][1]</code> - long name of zone in standard
   * time</li>
   * <li><code>zoneStrings[i][2]</code> - short name of zone in
   * standard time</li>
   * <li><code>zoneStrings[i][3]</code> - long name of zone in daylight
   * saving time</li>
   * <li><code>zoneStrings[i][4]</code> - short name of zone in daylight
   * saving time</li>
   * </ul>
   * The zone ID is <em>not</em> localized; it's one of the valid IDs of
   * the {@link java.util.TimeZone TimeZone} class that are not
   * <a href="../util/TimeZone.html#CustomID">custom IDs</a>.
   * All other entries are localized names.
   *
   * @param newZoneStrings the new time zone strings.
   * @throws IllegalArgumentException if the length of any row in <code>newZoneStrings</code> is
   * less than 5
   * @throws NullPointerException if <code>newZoneStrings</code> is null
   * @see #getZoneStrings()
   */
  public void setZoneStrings(String[][] newZoneStrings) {
    String[][] aCopy = new String[newZoneStrings.length][];
    for (int i = 0; i < newZoneStrings.length; ++i) {
      int len = newZoneStrings[i].length;
      if (len < 5) {
        throw new IllegalArgumentException();
      }
      aCopy[i] = Arrays.copyOf(newZoneStrings[i], len);
    }
    zoneStrings = aCopy;
    isZoneStringsSet = true;
    cachedHashCode = 0;
  }

  /**
   * Gets localized date-time pattern characters. For example: 'u', 't', etc.
   *
   * @return the localized date-time pattern characters.
   */
  public String getLocalPatternChars() {
    return localPatternChars;
  }

  /**
   * Sets localized date-time pattern characters. For example: 'u', 't', etc.
   *
   * @param newLocalPatternChars the new localized date-time pattern characters.
   */
  public void setLocalPatternChars(String newLocalPatternChars) {
    // Call toString() to throw an NPE in case the argument is null
    localPatternChars = newLocalPatternChars.toString();
    cachedHashCode = 0;
  }

  /**
   * Overrides Cloneable
   */
  public Object clone() {
    try {
      DateFormatSymbols other = (DateFormatSymbols) super.clone();
      copyMembers(this, other);
      return other;
    } catch (CloneNotSupportedException e) {
      throw new InternalError(e);
    }
  }

  /**
   * Override hashCode.
   * Generates a hash code for the DateFormatSymbols object.
   */
  @Override
  public int hashCode() {
    int hashCode = cachedHashCode;
    if (hashCode == 0) {
      hashCode = 5;
      hashCode = 11 * hashCode + Arrays.hashCode(eras);
      hashCode = 11 * hashCode + Arrays.hashCode(months);
      hashCode = 11 * hashCode + Arrays.hashCode(shortMonths);
      hashCode = 11 * hashCode + Arrays.hashCode(weekdays);
      hashCode = 11 * hashCode + Arrays.hashCode(shortWeekdays);
      hashCode = 11 * hashCode + Arrays.hashCode(ampms);
      hashCode = 11 * hashCode + Arrays.deepHashCode(getZoneStringsWrapper());
      hashCode = 11 * hashCode + Objects.hashCode(localPatternChars);
      cachedHashCode = hashCode;
    }

    return hashCode;
  }

  /**
   * Override equals
   */
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj == null || getClass() != obj.getClass()) {
      return false;
    }
    DateFormatSymbols that = (DateFormatSymbols) obj;
    return (Arrays.equals(eras, that.eras)
        && Arrays.equals(months, that.months)
        && Arrays.equals(shortMonths, that.shortMonths)
        && Arrays.equals(weekdays, that.weekdays)
        && Arrays.equals(shortWeekdays, that.shortWeekdays)
        && Arrays.equals(ampms, that.ampms)
        && Arrays.deepEquals(getZoneStringsWrapper(), that.getZoneStringsWrapper())
        && ((localPatternChars != null
        && localPatternChars.equals(that.localPatternChars))
        || (localPatternChars == null
        && that.localPatternChars == null)));
  }

  // =======================privates===============================

  /**
   * Useful constant for defining time zone offsets.
   */
  static final int millisPerHour = 60 * 60 * 1000;

  /**
   * Cache to hold DateFormatSymbols instances per Locale.
   */
  private static final ConcurrentMap<Locale, SoftReference<DateFormatSymbols>> cachedInstances
      = new ConcurrentHashMap<>(3);

  private transient int lastZoneIndex = 0;

  /**
   * Cached hash code
   */
  transient volatile int cachedHashCode = 0;

  private void initializeData(Locale desiredLocale) {
    locale = desiredLocale;

    // Copy values of a cached instance if any.
    SoftReference<DateFormatSymbols> ref = cachedInstances.get(locale);
    DateFormatSymbols dfs;
    if (ref != null && (dfs = ref.get()) != null) {
      copyMembers(dfs, this);
      return;
    }

    // Initialize the fields from the ResourceBundle for locale.
    LocaleProviderAdapter adapter = LocaleProviderAdapter
        .getAdapter(DateFormatSymbolsProvider.class, locale);
    // Avoid any potential recursions
    if (!(adapter instanceof ResourceBundleBasedAdapter)) {
      adapter = LocaleProviderAdapter.getResourceBundleBased();
    }
    ResourceBundle resource = ((ResourceBundleBasedAdapter) adapter).getLocaleData()
        .getDateFormatData(locale);

    // JRE and CLDR use different keys
    // JRE: Eras, short.Eras and narrow.Eras
    // CLDR: long.Eras, Eras and narrow.Eras
    if (resource.containsKey("Eras")) {
      eras = resource.getStringArray("Eras");
    } else if (resource.containsKey("long.Eras")) {
      eras = resource.getStringArray("long.Eras");
    } else if (resource.containsKey("short.Eras")) {
      eras = resource.getStringArray("short.Eras");
    }
    months = resource.getStringArray("MonthNames");
    shortMonths = resource.getStringArray("MonthAbbreviations");
    ampms = resource.getStringArray("AmPmMarkers");
    localPatternChars = resource.getString("DateTimePatternChars");

    // Day of week names are stored in a 1-based array.
    weekdays = toOneBasedArray(resource.getStringArray("DayNames"));
    shortWeekdays = toOneBasedArray(resource.getStringArray("DayAbbreviations"));

    // Put a clone in the cache
    ref = new SoftReference<>((DateFormatSymbols) this.clone());
    SoftReference<DateFormatSymbols> x = cachedInstances.putIfAbsent(locale, ref);
    if (x != null) {
      DateFormatSymbols y = x.get();
      if (y == null) {
        // Replace the empty SoftReference with ref.
        cachedInstances.put(locale, ref);
      }
    }
  }

  private static String[] toOneBasedArray(String[] src) {
    int len = src.length;
    String[] dst = new String[len + 1];
    dst[0] = "";
    for (int i = 0; i < len; i++) {
      dst[i + 1] = src[i];
    }
    return dst;
  }

  /**
   * Package private: used by SimpleDateFormat
   * Gets the index for the given time zone ID to obtain the time zone
   * strings for formatting. The time zone ID is just for programmatic
   * lookup. NOT LOCALIZED!!!
   *
   * @param ID the given time zone ID.
   * @return the index of the given time zone ID.  Returns -1 if the given time zone ID can't be
   * located in the DateFormatSymbols object.
   * @see java.util.SimpleTimeZone
   */
  final int getZoneIndex(String ID) {
    String[][] zoneStrings = getZoneStringsWrapper();

        /*
         * getZoneIndex has been re-written for performance reasons. instead of
         * traversing the zoneStrings array every time, we cache the last used zone
         * index
         */
    if (lastZoneIndex < zoneStrings.length && ID.equals(zoneStrings[lastZoneIndex][0])) {
      return lastZoneIndex;
    }

        /* slow path, search entire list */
    for (int index = 0; index < zoneStrings.length; index++) {
      if (ID.equals(zoneStrings[index][0])) {
        lastZoneIndex = index;
        return index;
      }
    }

    return -1;
  }

  /**
   * Wrapper method to the getZoneStrings(), which is called from inside
   * the java.text package and not to mutate the returned arrays, so that
   * it does not need to create a defensive copy.
   */
  final String[][] getZoneStringsWrapper() {
    if (isSubclassObject()) {
      return getZoneStrings();
    } else {
      return getZoneStringsImpl(false);
    }
  }

  private String[][] getZoneStringsImpl(boolean needsCopy) {
    if (zoneStrings == null) {
      zoneStrings = TimeZoneNameUtility.getZoneStrings(locale);
    }

    if (!needsCopy) {
      return zoneStrings;
    }

    int len = zoneStrings.length;
    String[][] aCopy = new String[len][];
    for (int i = 0; i < len; i++) {
      aCopy[i] = Arrays.copyOf(zoneStrings[i], zoneStrings[i].length);
    }
    return aCopy;
  }

  private boolean isSubclassObject() {
    return !getClass().getName().equals("java.text.DateFormatSymbols");
  }

  /**
   * Clones all the data members from the source DateFormatSymbols to
   * the target DateFormatSymbols. This is only for subclasses.
   *
   * @param src the source DateFormatSymbols.
   * @param dst the target DateFormatSymbols.
   */
  private void copyMembers(DateFormatSymbols src, DateFormatSymbols dst) {
    dst.eras = Arrays.copyOf(src.eras, src.eras.length);
    dst.months = Arrays.copyOf(src.months, src.months.length);
    dst.shortMonths = Arrays.copyOf(src.shortMonths, src.shortMonths.length);
    dst.weekdays = Arrays.copyOf(src.weekdays, src.weekdays.length);
    dst.shortWeekdays = Arrays.copyOf(src.shortWeekdays, src.shortWeekdays.length);
    dst.ampms = Arrays.copyOf(src.ampms, src.ampms.length);
    if (src.zoneStrings != null) {
      dst.zoneStrings = src.getZoneStringsImpl(true);
    } else {
      dst.zoneStrings = null;
    }
    dst.localPatternChars = src.localPatternChars;
    dst.cachedHashCode = 0;
  }

  /**
   * Write out the default serializable data, after ensuring the
   * <code>zoneStrings</code> field is initialized in order to make
   * sure the backward compatibility.
   *
   * @since 1.6
   */
  private void writeObject(ObjectOutputStream stream) throws IOException {
    if (zoneStrings == null) {
      zoneStrings = TimeZoneNameUtility.getZoneStrings(locale);
    }
    stream.defaultWriteObject();
  }
}
